Scientists Debate What to Do When Findings Aid an Enemy

By GINA KOLATA

Published: September 25, 2001

In 1975, a 30-year-old electrical engineering researcher at Stanford had an idea for a new kind of cryptography. He thought his method could give the public truly unbreakable codes for their communications and other data, codes even more powerful than those produced by the National Security Agency, the nation's premier code-making and code-breaking agency.

''I remember thinking, 'I've got a tiger by the tail,' '' said the scientist, Dr. Martin Hellman, now an emeritus professor of electrical engineering at Stanford. Sure enough, the N.S.A. soon stepped in and tried to control the dissemination of the work. The new technology could be so valuable to an enemy, the agency worried, that it should be classified at birth.

Dr. Hellman and others resisted. They said that the agency's threats to restrict them were violations of academic freedom, an unwarranted limitation on their right to publish and discuss new ideas. And they worried about the harm that could be done to national security if the technology were kept from the private sector, leaving its corporate data and private communications vulnerable to eavesdroppers, terrorists and hostile governments.

In the end, the academic scientists prevailed. They freely published their research on how to make codes. And companies soon sprang up to sell them.

But now, in the aftermath of the terrorist attacks on New York and the Pentagon, Dr. Hellman and others whose work spawned the commercialization of high-level cryptography are wondering if they did the right thing. They are haunted by the idea that law enforcement agencies may have figured out what the terrorists were planning, if only powerful encryption techniques had been kept secret.

And even if these particular terrorists relied on hand-delivered notes and other forms of communication not vulnerable to eavesdropping, what about other terrorists who might be lurking?

''Everything's changed,'' Dr. Hellman said.

When the technology was new, though, the issues looked clear-cut. Of course cryptography should be easily available to everyone, Dr. Hellman and other academic researchers argued. Twenty-five years ago, he said, ''I saw myself as Luke Skywalker and the N.S.A. as Darth Vader.'' Several years later, he said, ''in a period of deep personal introspection, I saw how human but how ridiculous that view was.''

But now, he said, with the country searching for terror suspects, the old questions have resurfaced with new force. ''I could say, I made exactly the right decision,'' he said, ''or I could say, If I could have envisioned this, I would never have published those papers.''

It probably is too late to take back cryptography even if people wanted to, experts say. But the ''what if?'' games of history can leave an indelible mark on today's debates over how, and whether, to control new technologies that can transform balances of power and be used for good and evil.

Already, arguments have begun over a very different science, nanotechnology -- the use of molecular machines to build structures atom by atom. At least one nanotechnology researcher, Dr. Ralph C. Merkle, started out in cryptography -- he worked with Dr. Hellman -- and so, for him, the new debate almost gives him a sense of déjà vu.

Nanotechnology could produce computers so powerful that today's machines would seem like clunky toys. And it could produce weapons with the power of a supercomputer embedded on the head of a bullet.

It could provide tiny robots to go into blood vessels and clean out plaque -- or microscopic robots that could kill instead of heal, and in ways far more predictable and precise than anything envisioned in germ warfare. One nanotechnology expert, Glenn H. Reynolds, a law professor at the University of Tennessee, said that someday it might even be used to make tiny robots that would lodge in people's brains and make them truly love Big Brother.

It is a technology whose consequences could be so terrifying that one scientist, Dr. K. Eric Drexler, who saw what it could do, at first thought that he should never tell anyone what he was imagining, for fear that those dreadful abuses might come to pass.

Scientists struggling with the promise and peril of nanotechnology say they look at the issues that arose with cryptography and see chilling parallels. Once again, they say, advances in technology are creating thorny moral issues. And once again, there are no easy answers on how to proceed.

The cryptography story unfolded in the years just after Watergate, when many academic scientists distrusted the federal government, and at a time when banks and other corporations were becoming concerned that their electronic data were insecure.

The academic scientists came up with a startling idea. Encryption is a way of scrambling data and, for quite some time, this has meant using mathematical formulas to transform data -- words or numbers, say, into strings of unreadable data. Dr. Hellman and Dr. Merkle, who now works for Zyvex, a nanotechnology company in Richardson, Tex., and Dr. Whitfield Diffie, a student of Dr. Hellman who now works for Sun Microsystems, decided to exploit ancient and unsolvable mathematical problems. If a code were designed so that anyone who wanted to break it would have to solve one of these problems, that code would be unbreakable.

It was the start of what became a large-scale movement of cryptography out of the secretive offices of the National Security Agency and into the halls of academe and, later, makers of commercial cryptographic systems.

And despite its efforts to limit the spread of the new encryption methods, the National Security Agency ultimately was unsuccessful. Hundreds of codes are available and those who want to keep data secret can do so.

''The debate was always about drawing the line between the ability to gather foreign intelligence and to protect U.S. intelligence and the ability to protect the computation and communications infrastructure and to have privacy,'' said Dr. Leonard Adleman, a professor of computer science at the University of Southern California. He is the ''A'' in the R.S.A. code, perhaps the most successful of these codes, which he invented with Dr. Ronald Rivest of the Massachusetts Institute of Technology and Dr. Adi Shamir, who is now at the Weizmann Institute of Science in Israel.

The decision to make powerful codes available to the general public allowed people to protect their privacy and businesses to protect their records and communications from prying eyes. But, Dr. Adleman noted: ''We do give up some of our ability to gather foreign intelligence. Everyone regrets that that is a byproduct.''

The lesson from cryptography, however, is that troubling questions about the possible uses of new technology will not stop the technologies from being publicly studied, Dr. Merkle said. Nor should those worries stop scientists from making their findings public, he added.

It is an issue that also came up in another context in biology in the 1970's when scientists, worried less about terrorists than natural disasters, asked whether they should pursue a new technology.

Molecular biologists had discovered how to remove genes from one cell and put them in another. They realized that they could do great good, turning bacteria into drug-producing factories, for example. But they also worried that they might accidentally create new and deadly bacteria that could spread cancer as easily as a common cold or create infections that no antibiotics could cure.

Worried about the implications of their own work, a group of these researchers met at Asilomar Conference Center in Pacific Grove, Calif., in 1975 to discuss how to proceed. They decided to hold off on their experiments until they could prove the work was safe. In just a few years, their fears were assuaged and the work continued.

With the Asilomar discussions as a model, a group of scientists and others who worried about nanotechnology formed a nonprofit institute, the Foresight Institute based in Los Altos, Calif. Its goal is to prepare society for the transforming powers of new technologies, and, in particular, of nanotechnology. Dr. Merkle is on its board of directors.

The institute's chairman, Dr. Drexler, originally thought that the best thing to do would be never to disclose nanotechnology's darker possibilities for fear it might give terrorists ideas. But he soon realized that if he could think of these abuses, others could too. So he decided to try to help society prepare for the good uses of the technology and to protect itself against its evil use.

''There's an argument that perhaps we could simply close our eyes to new technology,'' Dr. Merkle said. ''Occasionally, people argue that if new technologies pose new risks we should tell people they should not develop them.'' But then, he said, society would be worse off. ''Not only do we lose the benefits of the new technology, but we also -- and more importantly -- fail to understand what the new technology means,'' Dr. Merkle said. ''Then how can we defend ourselves if someone else develops them?''

Professor Reynolds, a member of the board of directors of the Foresight Institute, agreed. ''Barring some new scientific law that makes nanotechnology infeasible, you're going to have it sooner or later,'' he said. ''There is a lot of potential for abuse,'' he added, but if a ban on the research were instituted, society would be ''at the mercy of whoever breaks the ban.'' Those who broke the ban would have the weapons; the rest of the world would have no antidotes.

And yet, he added, the events of Sept. 11 show that opponents may not need high-tech weapons to do grave harm.

''We spend a lot of time worrying about extremely sophisticated threats,'' he said. ''But less sophisticated threats can slip under the radar. People who want to hurt you can find a way to do it.''

Nonetheless, said Dr. Adleman, the troubling questions that he faced two decades ago on controlling encryption remain. And the cryptography debates offer lessons for the development of other technologies.

''Now is an appropriate time to see if we made the right choice,'' Dr. Adleman said. ''The issue remains the same: Where do you draw that line?''

It is not easy. ''Who's smart enough to make these decisions?'' Dr. Adleman asked. ''You need the wisdom of Solomon.''

Photos: Dr. Ralph C. Merkle says troubling questions about the uses of new technology will not stop research. (Susan Spann for The New York Times); Dr. Leonard Adleman says he regrets the impact of encryption advances on gathering intelligence. (Ed Carreon for The New York Times)(pg. F2)